Summary
Craft CMS: Potential authenticated Remote Code Execution via referrer redirect
Requirements:
- Control panel access
- Permissions to edit an entry
Details
Control panel users with the ability to edit entries can execute unsandboxed Twig code via the HTTP Referrer header.
The issue happens when a user is saving entries. Strings for a signed redirect URL are being compiled as a Twig template via renderObjectTemplate(), and while a sandboxed alternative already exists (renderSandboxedObjectTemplate()), it is not used in this case. This signed URL can be specified by users, as it is reflected in the “Referer” HTTP request header, which is under attacker control.
This has been fixed in Craft 5.10.0. Affected users should update to that version or higher to get the fix.
Resources
Impact
Untrusted input is evaluated as executable code within the application's runtime environment. Typical impact: arbitrary code execution within the application's privilege context.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-55794? CVE-2026-55794 is a high-severity code injection vulnerability in craftcms/cms (composer), affecting versions >= 5.9.0, < 5.10.0. It is fixed in 5.10.0. Untrusted input is evaluated as executable code within the application's runtime environment.
- Which versions of craftcms/cms are affected by CVE-2026-55794? craftcms/cms (composer) versions >= 5.9.0, < 5.10.0 is affected.
- Is there a fix for CVE-2026-55794? Yes. CVE-2026-55794 is fixed in 5.10.0. Upgrade to this version or later.
- Is CVE-2026-55794 exploitable, and should I be worried? Whether CVE-2026-55794 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-55794 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-55794? Upgrade
craftcms/cmsto 5.10.0 or later.